Handover enhancement

Abstract

Example embodiments of the present disclosure relate to handover enhancements. In response to receiving a first message from the third device for initiating a handover related to the first device and the second device, the first device performs a handover procedure to the target cell indicated in the first message. The first device acts as a UE-to-network relay for the second device to communicate with the third device. The first device then sends at least one indication to the second device based on the handover procedure. In this manner, the remote UE can apply different operations based on respective indications associated with handover results. Accordingly, in a case where the handover is performed, the operation of the remote UE may be aligned with the operation of the relay UE, and system performance and reliability may be improved.

Description

Technical Field

[0001] Various exemplary embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to methods, devices, apparatuses, and computer-readable storage media for handover enhancement. Background Art

[0002] In the sidelink relay scenario, at least one remote UE may be connected to the network via a relay UE (also referred to as a UE-to-network relay UE). For example, the remote UE may be a wearable device (e.g., a smart watch, glasses, etc.). In the case of mobility, the relay UE and the connected remote UE(s) move together from one gNB (i.e., source gNB) to another gNB (i.e., target gNB), and the remote UE remains connected to the same relay UE. Depending on the operator policy or configuration, the PC5 configuration may or may not be the same in the source gNB and the target gNB. Therefore, the remote UE and the relay UE may use different RRC configurations, for example, security keys for communicating with the source gNB and the target gNB. Summary of the invention

[0003] Generally speaking, example embodiments of the present disclosure provide a solution for handover enhancement.

[0004] In a first aspect of the present disclosure, a first device is provided. The first device includes at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the first device to at least perform: in response to receiving a first message for initiating a handover related to the first device and the second device from a third device, performing a handover process to a target cellular cell indicated in the first message at the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device; and sending at least one indication to the second device based on the handover process.

[0005] In a second aspect of the present disclosure, a second device is provided. The second device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the second device to at least perform: receiving a second message from a third device via a first device, the second message including at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device; and receiving at least one indication corresponding to at least one condition in the set of conditions from the first device.

[0006] In a third aspect of the present disclosure, a third device is provided. The third device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the third device to at least perform: generating a second message according to a determination that a handover related to a first device and a second device is to be performed, the second message including at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device, and each condition in the set of conditions corresponding to at least one indication to be sent from the first device to the second device; sending a second message to the second device via the first device; and sending a first message for initiating a handover to the first device.

[0007] In a fourth aspect of the present disclosure, a method is provided. The method includes: in response to receiving a first message for initiating a handover related to a first device and a second device from a third device, performing a handover process at the first device to a target cell indicated in the first message, the first device acting as a UE-to-network relay for communication between the second device and the third device; and sending at least one indication to the second device based on the handover process.

[0008] In a fifth aspect of the present disclosure, a method is provided. The method includes: receiving a second message from a third device via a first device, the second message including at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device; and receiving at least one indication corresponding to at least one condition in the set of conditions from the first device.

[0009] In a sixth aspect of the present disclosure, a method is provided. The method includes: generating a second message at a third device according to a determination that a handover related to a first device and a second device is to be performed, the second message including at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device, and each condition in the set of conditions corresponding to at least one indication to be sent from the first device to the second device; sending the second message to the second device via the first device; and sending a first message for initiating the handover to the first device.

[0010] In a seventh aspect of the present disclosure, a first device is provided. The first device includes: a component for performing a handover process to a target cell indicated in the first message in response to receiving a first message for initiating a handover related to the first device and the second device from a third device, the first device acting as a UE-to-network relay for communication between the second device and the third device; and a component for sending at least one indication to the second device based on the handover process.

[0011] In an eighth aspect of the present disclosure, a second device is provided. The second device includes: a component for receiving a second message from a third device via a first device, the second message including at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device; and a component for receiving at least one indication corresponding to at least one condition in the set of conditions from the first device.

[0012] In a ninth aspect of the present disclosure, a third device is provided. The third device includes: a component for generating a second message including at least one candidate cell configuration and a set of conditions associated with the first device according to a determination that a handover related to the first device and the second device is to be performed, the first device acting as a UE-to-network relay for the second device to communicate with the third device, and each condition in the set of conditions corresponds to at least one indication to be sent from the first device to the second device; a component for sending the second message to the second device via the first device; and a component for sending a first message for initiating the handover to the first device.

[0013] In a tenth aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to any one of the fourth aspect, the fifth aspect, or the sixth aspect.

[0014] It should be understood that the present invention summary is not intended to identify the key or essential features of the embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0016] Figure 1 An example communication environment is shown in which example embodiments of the present disclosure may be implemented;

[0017] Figure 2 shows a signaling diagram for handover of a first device and a second device according to some example embodiments of the present disclosure;

[0018] Figure 3 A flowchart showing a method implemented at a first device according to some example embodiments of the present disclosure is shown;

[0019] Figure 4 A flowchart showing a method implemented at a second device according to some example embodiments of the present disclosure is shown;

[0020] Figure 5A flowchart of a method implemented at a third device according to some example embodiments of the present disclosure is shown;

[0021] Figure 6 shows a simplified block diagram of a device suitable for implementing an example embodiment of the present disclosure; and

[0022] Figure 7 A block diagram of an example computer-readable medium is shown according to some example embodiments of the present disclosure.

[0023] The same or similar reference numerals refer to the same or similar elements throughout the drawings. DETAILED DESCRIPTION

[0024] The principle of the present disclosure will now be described with reference to some example embodiments. It should be understood that these embodiments are described only for illustrative purposes, and help those skilled in the art to understand and implement the present disclosure, without implying any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways except for the way described below.

[0025] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0026] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an example embodiment, it is considered to be within the knowledge of those skilled in the art to affect such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0027] It should be understood that although the terms "first" and "second" etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish the functions of the various elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0028] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprise", "include", "have", "have", "include" and / or "include" when used herein specify the presence of stated features, elements and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0029] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is combined by “and” or “or”, means at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0030] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware circuit implementation only (such as analog implementation and / or digital circuit only) and (b) a combination of hardware circuitry and software, such as (where applicable): (i) a combination of analog and / or digital hardware circuits and software / firmware and (ii) any portion of a hardware processor(s) with software (including A digital signal processor, software and memory(s) that work together to enable a device (such as a mobile phone or server) to perform various functions) and (c) Hardware circuits and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate, but which may not be present when the software is not required to operate.

[0031] The definition of circuitry applies to all uses of the term in this application, including any claims. As yet another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example (and if applicable to a particular claim element), a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0032] As used herein, the term "communication network" refers to a network that follows any suitable communication standard, such as a fifth generation (5G) system, long term evolution (LTE), advanced LTE (LTE-A), wideband code division multiple access (WCDMA), high speed packet access (HSPA), narrowband Internet of Things (NB-IoT), etc. In addition, the communication between the terminal equipment and the network equipment in the communication network can be performed according to any suitable generation of communication protocols, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) new radio (NR) communication protocol and / or any other protocol currently known or developed in the future. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communication, there will certainly be communication technologies and systems of future types that can embody the present disclosure. It should not be considered that the scope of the present disclosure is limited to the aforementioned system.

[0033] As used herein, the term "network device" refers to a node in a communication network via which a terminal device accesses the network and receives services from it. Depending on the terminology and technology applied, a network device may refer to a base station (BS) or a radio access network (RAN) node or an access point (AP), for example, a Node B (Node B or NB), an evolved NodeB (e Node B or eNB), a next generation NodeB (NR NB or gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), an integrated access and backhaul (IAB) node, a relay, a low power node (such as a femto, pico, etc.). A network device is allowed to be defined as part of a gNB, for example in a CU / DU split, in which case the network device is defined as a gNB central unit (g NB-CU) or a gNB distributed unit (g NB-DU).

[0034] The term "terminal device" refers to any terminal device capable of wireless communication. As an example and not limitation, a terminal device may also be referred to as a communication device, a user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS), or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local ring phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device such as a digital camera, a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded device (LEE), a laptop mounted device (LME), a USB dongle, a smart device, a wireless customer premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated processing chain), consumer electronic devices, equipment operating on a commercial and / or industrial wireless network, etc. The terminal device may also correspond to the mobile terminal (MT) part of an integrated access and backhaul (IAB) node (also known as a relay node). In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

[0035] Although the functions described herein may be performed in fixed and / or wireless network nodes in various example embodiments, in other example embodiments, the functions may be implemented in a user equipment device (such as a cellular phone or a tablet computer or a laptop computer or a desktop computer or a mobile IoT device or a fixed IoT device). This user equipment device may (for example) be appropriately equipped with corresponding capabilities as described in conjunction with fixed and / or wireless network nodes. The user equipment device may be a user equipment and / or a control device configured to control the user equipment when the user equipment is installed therein, such as a chipset or a processor. Examples of such functions include boot server functions and / or home subscriber servers, which may be implemented in a user equipment device by providing the user equipment device with software configured to cause the user equipment device to execute from the perspective of these functions / nodes. Example Environment

[0036] Figure 1 An example communication environment 100 is shown in which example embodiments of the present disclosure may be implemented. The communication environment 100 may be a communication system that supports sidelink relay. Figure 1 As shown, the communication environment 100 includes a first device 110 , a second device 120 , a third device 130 , and a fourth device 140 .

[0037] The first device 110 and the second device 120 may be terminal devices, such as UEs. Specifically, the first device 110 acts as a relay UE, which may also be referred to as a UE-to-network relay UE. The second device 120 acts as a remote UE, such as a smart watch, glasses, etc. Hereinafter, the first device 110 and the second device 120 may also be referred to as a relay UE 110 and a remote UE 120, respectively.

[0038] The third device 130 and the fourth device 140 may be network devices such as gNBs, transmission reception points (TRPs), etc. The third device 130 and the fourth device 140 provide cells 102 and 104 for radio coverage, respectively. Figure 1 In the example shown, the first device 110 is initially located within the cell 102 and is served by the third device 130. The second device 120 is outside the cell 102 and is connected to the network via the relay UE 110. Alternatively, as another example, the second device 120 may be inside the cell 102 but connected to the network via an indirect path via the relay UE 110. The first device 110 and the second device 120 may communicate with each other via the PC5 interface.

[0039] The fourth device 140 provides a neighboring cell 104. Hereinafter, the third device 130 and the fourth device 140 may also be referred to as a serving gNB 130 or a source gNB 130 and a target gNB 140, respectively. In addition, the cells 102 and 104 may also be referred to as a serving cell 102 and a neighboring cell 104 or a target cell 104, respectively. Figure 1 In the example shown, the first device 110 is capable of performing a handover from the serving cell 102 to the neighboring cell 104. The first device 110 may communicate with the third device 130 or the fourth device 140 via a Uu interface.

[0040] In some example embodiments, the link from the terminal device to the network device is referred to as an uplink (UL). Additionally, the link from the network device to the terminal device is referred to as a downlink (DL).

[0041] It should be understood that Figure 1 The number of devices and their connections shown in the figure is for illustrative purposes only and does not imply any limitation. The communication network 100 may include any suitable number of devices configured to implement the example embodiments of the present disclosure. Although not shown, it should be understood that one or more additional devices and connections may be deployed in the communication network 100.

[0042] Hereinafter, for the purpose of illustration, some example embodiments are described in which the first device 110 and the second device 120 operate as terminal devices (e.g., UEs), and the third device 130 and the fourth device 140 operate as network devices (e.g., gNBs, TRPs, etc.). However, in some example embodiments, the operations described in conjunction with the terminal device may be implemented at the network device or other devices, and the operations described in conjunction with the network device may be implemented at the terminal device or other devices.

[0043] The communication in the communication environment 100 can be implemented according to any appropriate (multiple) communication protocols, including but not limited to cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), etc., wireless local area network communication protocols such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol currently known or developed in the future. In addition, the communication can utilize any appropriate wireless communication technology, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiple access (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM) and / or any other technology currently known or developed in the future.

[0044] In order to hand over at least one remote UE to a target RAN node, the source RAN node sends a handover (HO) command to the at least one remote UE via the relay UE. The HO command may be carried in a radio resource control (RRC) reconfiguration message. This is performed while the relay UE is still connected to the source cell. However, if the at least one remote UE applies a new RRC configuration (e.g., a new security key associated with the target RAN node) immediately after receiving the HO command, this may cause the following problem: if the relay UE itself has not yet performed a HO to the target cell, traffic sent by the at least one remote UE based on the new RRC configuration cannot be forwarded to the target RAN node.

[0045] For example, the relay UE may detach from the source cell quite late after sending the RRC reconfiguration to the remote UE. Additionally or alternatively, the relay UE may not be able to connect to the target RAN node and need to reestablish the RRC connection with a different RAN node. This results in the remote UE erroneously applying the RRC reconfiguration that should be used to communicate with the target RAN node when the remote UE is still communicating with the source RAN node via the relay UE. In addition, the source RAN node needs to ensure that the reconfiguration for the connected remote UE is issued just before the reconfiguration for the relay UE. In some cases where the radio signal may degrade rapidly, there is no guarantee that all connected remote UEs receive the RRC reconfiguration just before the relay UE detaches from the source cell.

[0046] Therefore, it is desired that the relay UE and at least one remote UE may be handed over to the target cell together, and the RRC configuration on the source cell or the target cell is applied in a synchronized manner. Working principles and example signaling for communication

[0047] According to some example embodiments of the present disclosure, a HO solution is provided. In the solution, in response to receiving a first message for initiating HO related to a first device and a second device from a third device, the first device performs a HO process to a target cell indicated in the first message. The first device acts as a UE-to-network relay for the second device to communicate with the third device. Then, the first device sends at least one indication based on the HO process to the second device.

[0048] With this solution, at least one candidate cell configuration and a set of conditions associated with the relay UE are provided to at least one remote UE. The set of conditions includes at least a set of PC5 conditions or events. In the case where the source gNB initiates the HO process, the relay UE can send an indication of the PC5 condition or event associated with the HO process. Accordingly, the corresponding configuration will be triggered at the remote UE. In this way, the relay UE and the remote UE can be aligned with respect to their actions when performing HO and applying the corresponding configuration on the source cell or target cell.

[0049] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0050] Reference now Figure 2 , which shows a signaling diagram for switching between a first device and a second device according to some example embodiments of the present disclosure. Figure 2 As shown, process 200 involves first device 110, second device 120, third device 130, and fourth device 140. For discussion purposes, reference is made to Figure 1 The signaling flow 200 is described.

[0051] In process 200, the second device 120 (ie, remote UE) is initially connected to the third device 130 (ie, source gNB) via the first device 110 (ie, relay UE). Therefore, UL and DL data are transmitted 202 between the second device 120 and the third device 130 via the first device 110.

[0052] Third device 130 determines 204 that a HO related to first device 110 and second device 120 is to be performed. In some example embodiments, such a HO decision may be made based on a "group" indication from second device 120, or from first device 110, or from a core network (CN).

[0053] In some example embodiments, third device 130 may initiate 206 a HO preparation procedure for second device 120 by sending a HO request message to a neighboring gNB (e.g., fourth device 140). The HO request message may include a “group” indication and information of first device 110.

[0054] In some example embodiments, the fourth device 140 may accept the HO by replying 208 to the third device 130 with a HO request confirm message.

[0055] After receiving the HO Request Confirmation message, the third device 130 generates 210 a second message including at least one candidate cell configuration and a set of conditions associated with the first device 110. The second message may be, for example, an RRC Reconfiguration message, which may be regarded as a Conditional RRCReconfiguration message.

[0056] The set of conditions may include a set of PC5 conditions or events. In some example embodiments, the third device 130 may decide to add the set of PC5 conditions in the RRC reconfiguration message. This may be added in addition to or in place of the conditions based on Uu measurements in normal condition handover (CHO). For example, the RRC reconfiguration message may include both PC5 conditions and Uu conditions.

[0057] In some example embodiments, the term "conditional handover" or "CHO" refers to a handover performed by a UE when one or more handover execution conditions are met. Specifically, upon receiving a CHO configuration, the UE starts evaluating at least one execution condition and stops evaluating the at least one execution condition once the handover is performed.

[0058] The PC5 condition may refer to a condition used, for example, if the second device 120 maintains connection with the first device 110 and connects with the fourth device 140. The Uu condition may refer to a condition used, for example, if the second device 120 performs an indirect-to-direct path switch and connects with the fourth device 140.

[0059] In some example embodiments, the set of conditions may include at least one of the following: ● The condition of "suspending UL transmission", also known as the first condition, which is associated with suspending data transmission to the third device 130 via the second device 120: When the first condition is met, the second device 120 suspends UL transmission on the PC5 interface. The second device 120 can continue DL reception by using the current RRC reconfiguration (e.g., PC5 configuration and security key related to the third device 130). ● The condition for "resuming with new configuration", also known as the second condition, which is associated with resuming with one of at least one candidate cell configuration: When the second condition is met, the second device 120 performs the associated RRC reconfiguration and resumes UL transmission or DL reception by using the new configuration (e.g., PC5 configuration, security key related to the fourth device 140). ● The condition for "resuming with old configuration", also known as the third condition, which is associated with the source cell configuration: When the third condition is met, the second device 120 discards at least one candidate cell configuration and resumes UL transmission or DL reception by using the old configuration (e.g., security key related to the third device 130). ● The condition for "discarding and reconstructing", also known as the fourth condition, which is associated with discarding at least one candidate cell configuration and initiating a reconstruction process: When the fourth condition is met, the second device 120 discards at least one candidate cell configuration and initiates an RRC reconstruction process.

[0060] The third device 130 then sends 212 a second message (e.g., an RRC reconfiguration message) to the second device 120 via the first device 110. In some example embodiments, the second device 120 may buffer the received RRC reconfiguration message including the set of conditions.

[0061] Accordingly, the second device 120 may send 214 an RRC reconfiguration complete message to the third device 130 via the first device 110.

[0062] After receiving the RRC reconfiguration complete message, the third device 130 may initiate an HO preparation process for the first device 110 by sending 216 an HO request message, which includes a "group" indication and information about the associated remote UE (i.e., the second device 120).

[0063] In response to the HO request message, the fourth device 140 may send 218 an HO request confirmation message to the third device 130.

[0064] Accordingly, the third device 130 sends 220 a first message for initiating HO to the first device 110. The first message may be, for example, a HO command.

[0065] The HO command notifies the first device 110 that the HO is performed and the second device 120 is to be switched with the first device 110. In response to the first message, the first device 110 performs 222 a HO procedure to the target cell indicated in the first message. Specifically, the first device 110 may detach from the source cell 102. Figure 1 In the example of , the candidate cells may include the neighboring cells 104 .

[0066] Then, the first device 110 sends 224 at least one indication based on the HO procedure to the second device 120. As mentioned above, the set of conditions may correspond to the at least one indication.

[0067] Depending on the indication, the operation of second device 120 may be different. In some example embodiments, the at least one indication may include an indication that a HO procedure is initiated at first device 110. Accordingly, second device 120 may be notified that first device 110 is detaching from source cell 102.

[0068] Additionally or alternatively, the at least one indication may include an indication to suspend UL transmission from the second device 120 to the third device 130 via the first device 110. This indication may also be referred to as a "suspend" indication. As a result, upon receiving the indication from the first device 110 on PC5, the second device 120 may suspend UL transmission on PC5. The second device 120 may continue DL reception by applying the current RRC configuration (e.g., PC5 configuration and security keys associated with the serving gNB 130).

[0069] Note that the HO command to the second device 120 at step 212 may implicitly or explicitly indicate that the CHO is bound to the ongoing HO of the first device 110. Thus, in some cases, this may allow the HO start indication from the first device 110 to be skipped at step 224, since the second device 120 is already aware of the ongoing HO of the first device 110 and may have already suspended UL transmissions after receiving the HO command at step 212. However, transmitting the HO start indication may still be beneficial, since the time period between transmitting the HO command and transmitting the HO start indication at step 212 may vary. Thus, transmission of the HO start indication may allow the second device 120 to send UL data within the time period. It should be understood that transmission of the HO start indication may be performed prior to detaching from the source cell 102, or alternatively in parallel with detaching from the source cell 102.

[0070] In the above embodiment, upon receiving the indication, the second device 120 may detect that the first condition for “pausing UL transmission” is satisfied. Accordingly, the second device 120 may suspend 226 UL transmission. Additionally, in the case where the first device 110 still has buffered DL data for the second device 120, the first device 110 may continue to relay DL data to the second device 120.

[0071] If the HO process is successful, the first device 110 may be connected to the target cell 104. After the first device 110 is connected to the target cell 104, the first device 110 may send 228 a HO completion message to the fourth device 140. Additionally, the first device 110 may send 230 an indication of recovery using the target cell configuration to the second device 120 over the PC5 interface. The indication notifies the second device 120 to apply the buffered configuration associated with the target cell 104 and to resume transmission and reception of data and / or signaling with the target cell 104 via the first device 110.

[0072] In an example embodiment, the second device 120 may receive multiple RRCReconfigurations, and each RRCReconfiguration may correspond to a cell of the fourth device 140. In the case where the first device 110 connects with a specific cell of the fourth device 140 and notifies the second device 120 of the specific cell, the second device 120 should perform the associated RRCReconfiguration.

[0073] After receiving the indication to restore using the target cell configuration, the second device 120 may detect that the second condition for “restore using the new configuration” is satisfied. Accordingly, the second device 120 may execute 232 the previously buffered RRCReconfiguration.

[0074] Additionally, in some example embodiments, second device 120 may then send 234 a HO completion message to fourth device 140 via first device 110. Accordingly, UL and DL data is restored 236 between second device 120 and fourth device 140 via first device 110.

[0075] Otherwise, if the first device 110 fails to connect to the target cell 104 at step 222, in other words, the HO process fails, the first device 110 may reconnect to the source cell 102. In this case, the first device 110 may send an indication of "recovery with old configuration" to the second device 120 on PC5.

[0076] In the above embodiment, upon receiving the indication, the second device 120 may detect that the third condition for "recovery using the old configuration" is satisfied. In this case, the second device 120 may discard the previously buffered RRCR congulation of the target cell 104 and recover UL and DL data using the old configuration of the source cell 102.

[0077] Alternatively, in some example embodiments, if the first device 110 fails to connect to the target cell 104 at step 222, the first device 110 may not reconnect to the source cell 102, but reconnect to another gNB that is not prepared. In this case, the first device 110 may perform a reestablishment process with a cell of the other gNB, and the cell is different from the source cell 102 and at least one candidate cell. Then, the first device 110 may send a "discard and reestablish" indication to the second device 120 on PC5, which corresponds to the fourth condition.

[0078] In the above embodiment, after receiving the indication, the second device 120 may detect that the fourth condition for "discard and reestablish" is satisfied. Accordingly, the second device 120 may discard the previously buffered RRCReconfiguration and initiate the RRC reestablishment process.

[0079] It should be understood that some steps in process 200 are optional or can be omitted. In addition, the order of the steps is given for illustrative purposes, and steps in different orders or more or fewer steps may also be suitable for implementing the proposed solution. Therefore, the embodiments of the present disclosure are not limited in this regard.

[0080] According to an exemplary embodiment of the present disclosure, handover of a relay UE and a remote UE to the same target gNB can be performed together via a conditional RRCReconfiguration. The conditional RRCReconfiguration is triggered by a PC5 condition or event associated with the HO for the relay UE. As a result, in the case of performing a handover, the operation of the remote UE can be aligned with the operation of the relay UE, and system performance and reliability can be improved. Example Methods

[0081] Figure 3 FIG. 3 is a flowchart of a method 300 implemented at a first device according to some example embodiments of the present disclosure. For example, the first device may include a terminal device. For the purpose of discussion, Figure 1 The method 300 is described from the perspective of the first device 110.

[0082] At block 310, the first device 110 receives a first message for initiating a handover related to the first device 110 and the second device 120 from the third device 130. The first device 110 acts as a UE-to-network relay for the second device 120 to communicate with the third device 130. The third device 130 may act as a source gNB providing a serving cell 102 for the first device 110.

[0083] In response to receiving the first message, at block 320 , the first device 110 performs a handover procedure to the target cell indicated in the first message.

[0084] At block 330 , the first device 110 transmits at least one indication to the second device 120 based on the handover process.

[0085] In some example embodiments, sending at least one indication may include sending at least one of the following to second device 120: an indication that a switching process is initiated at first device 110, or an indication to suspend uplink transmission from second device 120 to third device 130 via first device 110.

[0086] In some example embodiments, the first device 110 may also be caused to perform: determining that at least one downlink data from the third device 130 to the second device 120 is buffered at the first device 110; and sending at least one downlink data to the second device 120 based on the determination that the at least one downlink data is buffered.

[0087] In some example embodiments, sending at least one indication may include: determining that a switching process is successfully performed to a target cell; and based on the determination that the switching process is successfully performed, sending an indication to the second device 120 for recovery using the target cell configuration, the indication instructing the second device 120 to apply a configuration related to the target cell and to resume data and / or signaling transmission and reception with the target cell via the first device 110.

[0088] In some example embodiments, sending at least one indication may include: determining that the handover procedure failed; and based on the determination that the first device 110 reconnects with the source cell after the handover procedure failed, sending an indication to the second device 120 to recover using the source cell configuration. The indication may instruct the second device 120 to apply the configuration related to the source cell 102 and to recover data and / or signaling transmission and reception with the source cell via the first device 110.

[0089] In some example embodiments, sending at least one indication may include: determining that a handover process fails; performing, based on the determination that the handover process fails, a reconstruction process with a cell other than a source cell and a target cell; and sending, based on the determination that the reconstruction process is successfully performed, a reconstruction indication to a second device 120, the reconstruction indication instructing the second device 120 to discard at least one candidate cell configuration and initiate a reconstruction process with the cell via a first device 110.

[0090] In some example embodiments, the first device 110 may include a relay terminal device. The second device 120 may include a remote terminal device. The third device 130 may include a network device.

[0091] Figure 4 A flowchart of an example method 400 implemented at a second device according to some example embodiments of the present disclosure is shown. For example, the second device may include a remote UE connected to a network via a relay UE. For purposes of discussion, method 400 will be described from Figure 1 the perspective of the second device 120 in

[0092] At 410, the second device 120 receives, via the first device 110, a second message from the third device 130, the second message including at least one candidate cell configuration and a set of conditions associated with the first device 110. The first device 110 acts as a UE-to-network relay for communication between the second device 120 and the third device 130.

[0093] In some example embodiments, the second message may include an RRC reconfiguration message and may further include a measurement configuration related to an interface (e.g., Uu interface) between the second device 120 and the third device 130.

[0094] In some example embodiments, the set of conditions may include at least one of the following: ● A first condition associated with pausing data transmission to the third device 130 via the first device 110, ● A second condition associated with resuming using one of the at least one candidate cell configurations, ● A third condition associated with resuming using a source cell configuration, ● A fourth condition associated with discarding the at least one candidate cell configuration and initiating a reconstruction process.

[0095] At 420, the second device 120 receives at least one indication corresponding to at least one condition in the set of conditions from the first device 110.

[0096] In some example embodiments, the method 400 further includes: in response to receiving the second message, determining that the first condition is satisfied; and suspending uplink transmission to the third device 130 via the first device 110 in accordance with the determination that the first condition is satisfied.

[0097] In some example embodiments, receiving at least one indication includes receiving an indication from the first device 110 that a handover process is initiated at the first device 110 , the indication corresponding to the first condition.

[0098] In some example embodiments, method 400 may further include: in response to receiving an indication corresponding to the first condition, determining that the first condition is satisfied; and suspending uplink transmission to third device 130 via first device 110 based on the determination that the first condition is satisfied.

[0099] In some example embodiments, method 400 may further include receiving, from first device 110 , at least one downlink data transmission sent by third device 130 .

[0100] In some example embodiments, receiving at least one indication may include receiving an indication from first device 110 to recover using a target cell configuration, the at least one candidate cell including the target cell, and the indication corresponding to the second condition.

[0101] In some example embodiments, method 400 may further include: in response to receiving the indication, determining that the second condition is satisfied; determining a target cell configuration from at least one candidate cell configuration based on the determination that the second condition is satisfied; and applying the target cell configuration and resuming data and / or signaling transmission and reception.

[0102] In some example embodiments, receiving at least one indication may include receiving an indication from first device 110 to recover using a source cell configuration, the indication corresponding to the third condition.

[0103] Additionally or alternatively, in some example embodiments, method 400 may further include: in response to receiving an indication, determining that a third condition is satisfied; based on the determination that the third condition is satisfied, discarding at least one candidate cell configuration; and applying the source cell configuration and resuming data and / or signaling transmission and reception.

[0104] In some example embodiments, receiving at least one indication may include receiving, from the first device 110, a reconstruction indication corresponding to the fourth condition.

[0105] In some example embodiments, the method 400 may further include: based on a determination that the fourth condition is satisfied, discarding at least one candidate cell configuration; and initiating a reestablishment procedure.

[0106] In some example embodiments, the first device 110 may include a relay terminal device, the second device 120 may include a remote terminal device, and the third device 130 may include a network device.

[0107] Figure 5 1 shows a flow chart of an example method 500 implemented at a third device according to some example embodiments of the present disclosure. For example, the third device may include a network device, such as a serving gNB. For the purpose of discussion, Figure 1 The method 500 is described from the perspective of the third device 130.

[0108] In block 510 , the third device 130 determines whether handover related to the first device 110 and the second device 120 is to be performed.

[0109] If the handover is to be performed, then at block 520, the third device 130 generates a second message that includes at least one candidate cell configuration and a set of conditions associated with the first device 110. The first device 110 acts as a UE-to-network relay for the second device 120 to communicate with the third device 130. Each condition in the set of conditions corresponds to at least one indication to be sent from the first device 110 to the second device 120.

[0110] In block 530 , the third device 130 sends a second message to the second device 120 via the first device 110 .

[0111] In block 540 , the third device 130 sends a first message for initiating handover to the first device 110 .

[0112] In some example embodiments, the second message may include an RRC reconfiguration message and further include a measurement configuration related to an interface between the second device 120 and the third device 130. The interface may be, for example, a Uu interface.

[0113] In some example embodiments, the set of conditions may include at least one of the following: a first condition associated with suspending the data transmission to the third device 130 via the second device 120, ●A second condition, which is associated with recovery using one of at least one candidate cell configuration, ●A third condition, which is associated with recovery using the source cell configuration, ●A fourth condition, which is associated with discarding at least one candidate cell configuration and initiating a reconstruction process.

[0114] In some example embodiments, the first device 110 may include a relay terminal device, the second device 120 may include a remote terminal device, and the third device 130 may include a network device. Example devices, equipment, and media

[0115] In some example embodiments, a first device (eg, Figure 1 The first device 110 in the embodiment may include a component for performing the corresponding operation of the method 300. The device may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The first device may be implemented as or included in Figure 1 In the first device 110.

[0116] In some example embodiments, the first device includes: a component for performing a handover procedure to a target cell indicated in the first message in response to receiving a first message from a third device for initiating a handover associated with the first device and a second device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; and a component for sending at least one indication to the second device based on the handover procedure.

[0117] In some example embodiments, the means for sending the at least one indication comprises means for sending to the second device at least one of: an indication that a switching process is initiated at the first device, or an indication to suspend uplink transmission from the second device to the third device via the first device.

[0118] In some example embodiments, the first device further includes: a component for determining that at least one downlink data from the third device to the second device is buffered at the first device; and a component for sending at least one downlink data to the second device based on the determination that the at least one downlink data is buffered.

[0119] In some example embodiments, the component for sending at least one indication includes: a component for determining that a handover procedure is successfully performed to a target cell; and a component for sending an indication to a second device for recovery using a target cell configuration based on the determination that the handover procedure is successfully performed, the indication instructing the second device to apply a configuration related to the target cell and to resume data and / or signaling transmission and reception with the target cell via the first device.

[0120] In some example embodiments, the component for sending at least one indication includes: a component for determining that a handover process has failed; and a component for sending an indication to a second device for recovery using a source cell configuration based on a determination that the first device has reconnected with the source cell after the handover process has failed, the indication instructing the second device to apply a configuration related to the source cell and to resume data and / or signaling transmission and reception with the source cell via the first device.

[0121] In some example embodiments, the component for sending at least one indication includes: a component for determining that a handover process has failed; a component for performing a reestablishment process with a cell other than a source cell and a target cell based on the determination that the handover process has failed; and a component for sending a reestablishment indication to a second device based on a determination that the reestablishment process has been successfully performed, the reestablishment indication instructing the second device to discard at least one candidate cell configuration and initiate a reestablishment process with the cell via the first device.

[0122] In some example embodiments, the first apparatus comprises a relay terminal device, the second apparatus comprises a remote terminal device, and the third apparatus comprises a network device.

[0123] In some example embodiments, a second device (eg, Figure 1 The second device 120 in the method 400 may include a component for performing the corresponding operation of the method 400. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The second device may be implemented as or included in Figure 1 In the second device 120.

[0124] In some example embodiments, the second device includes: a component for receiving a second message including at least one candidate cell configuration and a set of conditions associated with the first device from a third device via the first device, the first device acting as a UE-to-network relay for communication between the second device and the third device; and a component for receiving at least one indication corresponding to at least one condition in the set of conditions from the first device.

[0125] In some example embodiments, the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second apparatus and the third apparatus.

[0126] In some example embodiments, the set of conditions includes at least one of: a first condition associated with suspending data transmission to a third device via the first device, a second condition associated with recovering using one of at least one candidate cell configurations, a third condition associated with recovering using a source cell configuration, and a fourth condition associated with discarding at least one candidate cell configuration and initiating a reconstruction process.

[0127] In some example embodiments, the second apparatus further comprises: means for determining, in response to receiving the second message, that the first condition is satisfied; and means for suspending uplink transmission to the third apparatus via the first apparatus based on the determination that the first condition is satisfied.

[0128] In some example embodiments, means for receiving at least one indication comprises receiving an indication from the first apparatus that a handover process is initiated at the first apparatus, the indication corresponding to the first condition.

[0129] In some example embodiments, the second device further includes: a component for determining that the first condition is satisfied in response to receiving an indication corresponding to the first condition; and a component for suspending uplink transmission to the third device via the first device based on the determination that the first condition is satisfied.

[0130] In some example embodiments, the second apparatus further comprises means for receiving, from the first apparatus, at least one downlink data transmission sent by the third apparatus.

[0131] In some example embodiments, means for receiving at least one indication includes means for receiving, from the first apparatus, an indication to recover using a target cell configuration, the at least one candidate cell including the target cell, and the indication corresponding to the second condition.

[0132] In some example embodiments, the second apparatus further comprises: means for determining, in response to receiving the indication, that the second condition is satisfied; means for determining, based on the determination that the second condition is satisfied, a target cell configuration from at least one candidate cell configuration; and means for applying the target cell configuration and resuming data and / or signaling transmission and reception.

[0133] In some example embodiments, means for receiving at least one indication includes means for receiving an indication from the first apparatus to recover using the source cell configuration, the indication corresponding to the third condition.

[0134] In some example embodiments, the second apparatus further comprises: means for determining, in response to receiving an indication, that a third condition is satisfied; means for discarding at least one candidate cell configuration based on a determination that the third condition is satisfied; and means for applying the source cell configuration and resuming data and / or signaling transmission and reception.

[0135] In some example embodiments, the means for receiving at least one indication comprises means for receiving a reestablishment indication corresponding to the fourth condition from the first device.

[0136] In some example embodiments, the second apparatus further comprises: means for discarding at least one candidate cell configuration based on a determination that the fourth condition is satisfied; and means for initiating a re-establishment procedure.

[0137] In some example embodiments, the first apparatus comprises a relay terminal device, the second apparatus comprises a remote terminal device, and the third apparatus comprises a network device.

[0138] In some example embodiments, a third device (eg, Figure 1 The third device 130 in the method 500 may include a component for performing the corresponding operation of the method 500. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The second device may be implemented as or included in Figure 1 In the third device 130.

[0139] In some example embodiments, the third device includes: a component for generating a second message including at least one candidate cell configuration and a set of conditions associated with the first device based on a determination that a handover related to the first device and the second device is to be performed, the first device acting as a UE-to-network relay for the second device to communicate with the third device, wherein each condition in the set of conditions corresponds to at least one indication to be sent from the first device to the second device; a component for sending the second message to the second device via the first device; and a component for sending a first message to the first device for initiating the handover.

[0140] In some example embodiments, the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second apparatus and the third apparatus.

[0141] In some example embodiments, the set of conditions includes at least one of: a first condition associated with suspending data transmission to a third device via the second device, a second condition associated with recovering using one of at least one candidate cell configurations, a third condition associated with recovering using a source cell configuration, and a fourth condition associated with discarding at least one candidate cell configuration and initiating a reconstruction process.

[0142] In some example embodiments, the first apparatus comprises a relay terminal device, the second apparatus comprises a remote terminal device, and the third apparatus comprises a network device.

[0143] Figure 6 6 is a simplified block diagram of a device 600 suitable for implementing an example embodiment of the present disclosure. The device 600 may be provided for implementing an electronic device, such as Figure 1 The first device 110, the second device 120, the third device 130 or the fourth device 140 shown in FIG. As shown in the figure, the device 600 includes one or more processors 610, one or more memories 620 coupled to the processor 610, and one or more communication modules 640 coupled to the processor 610.

[0144] The communication module 640 is used for two-way communication. The communication module 640 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface may represent any interface necessary to communicate with other network elements. In some example embodiments, the communication module 640 may include at least one antenna.

[0145] Processor 610 may be of any type suitable for the local technology network, and may include one or more of the following: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture (as non-limiting examples). Device 600 may have multiple processors, such as application specific integrated circuit chips that are time slaved to a clock of a synchronized main processor.

[0146] The memory 620 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 624, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), optical disk, laser disk, and other magnetic storage and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 622 and other volatile memories that are not retained during power failure.

[0147] The computer program 630 includes computer executable instructions executed by the associated processor 610. The instructions of the program 630 may include instructions for performing the operations / actions of some example embodiments of the present disclosure. The program 630 may be stored in a memory, such as ROM 624. The processor 610 may perform any suitable actions and processes by loading the program 630 into the RAM 622.

[0148] The exemplary embodiments of the present disclosure may be implemented by means of a program 630, so that the device 600 may execute the Figures 2 to 5 Any process of the present disclosure discussed. The exemplary embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0149] In some example embodiments, program 630 may be tangibly embodied in a computer-readable medium, which may be included in device 600 (such as in memory 620) or other storage devices accessible to device 600. Device 600 may load program 630 from the computer-readable medium into RAM 622 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. As used herein, the term "non-transitory" is a limitation of the medium itself (i.e., tangible, rather than a signal), rather than a limitation on the persistence of data storage (e.g., RAM compared to ROM).

[0150] Figure 7 An example of a computer-readable medium 700 is shown, which may be in the form of a CD, DVD, or other optical storage disk. Program 630 is stored on computer-readable medium 700.

[0151] Generally, the various embodiments of the present disclosure may be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software executable by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, by way of non-limiting example, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, special-purpose circuits or logic, general-purpose hardware or controllers, or other computing devices, or some combination thereof.

[0152] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium (such as a non-transitory computer-readable medium). The computer program product includes computer-executable instructions, such as those included in program modules executed in a device on a target physical or virtual processor, to perform any of the methods described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules may be combined or split as needed among program modules. The machine-executable instructions for program modules may be executed within local or distributed devices. In a distributed device, program modules may be located in both local and remote storage media.

[0153] The program code for executing the method of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device so that the program code enables the functions / operations specified in the flow chart and / or block diagram to be implemented when executed by the processor or controller. The program code can be executed entirely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0154] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0155] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing. More specific examples of computer readable storage media would include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0156] In addition, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown or in sequence, or performing all of the operations shown to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of the present disclosure, but should be interpreted as descriptions of features that may be specific to a particular embodiment. Unless explicitly stated, certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, unless explicitly stated, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0157] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first device, include: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the first device to at least perform: In response to receiving a first message for initiating a handover associated with the first device and the second device from a third device, performing a handover procedure at the first device to a target cell indicated in the first message, the first device acting as a UE-to-network relay for the second device to communicate with the third device; as well as Based on the switching process, at least one indication is sent to the second device.

2. The first device according to claim 1, wherein sending the at least one indication include: Sending at least one of the following to the second device: an indication that the handover procedure is initiated at the first device, or An indication of suspending uplink transmission from the second device to the third device via the first device.

3. The first device of claim 2, wherein the first device is further caused to execute: determining that at least one downlink data from the third device to the second device is buffered at the first device; According to a determination that the at least one downlink data is buffered, the at least one downlink data is sent to the second device.

4. The first device according to any one of claims 1 to 3, wherein sending the at least one indication include: determining that the handover procedure is successfully performed to the target cell; as well as Based on the determination that the handover process is successfully performed, an indication to resume using the target cell configuration is sent to the second device, the indication instructing the second device to apply the configuration related to the target cell and resume data and / or signaling transmission and reception with the target cell via the first device.

5. The first device according to any one of claims 1 to 3, wherein sending the at least one indication include: Determining that the switching process fails; as well as Based on the determination that the first device is reconnected with the source cell after the switching process fails, an indication is sent to the second device to recover using the source cell configuration, wherein the indication instructs the second device to apply the configuration related to the source cell and to resume data and / or signaling transmission and reception with the source cell via the first device.

6. The first device according to any one of claims 1 to 3, wherein sending the at least one indication include: Determining that the switching process fails; Based on the determination of the handover process failure, performing a reestablishment process with cells other than the source cell and the target cell; as well as Based on a determination that the re-establishment procedure is successfully performed, a re-establishment indication is sent to the second device, the re-establishment indication instructing the second device to discard at least one candidate cell configuration and initiate a re-establishment procedure with the cell via the first device.

7. The first device according to claim 1, wherein the first device comprises a relay terminal device, the second device comprises a remote terminal device, and the third device comprises a network device.

8. A second device, include: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the second device to at least perform: receiving, via a first device, a second message from a third device, the second message comprising at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; as well as At least one indication corresponding to at least one condition in the set of conditions is received from the first device.

9. The second device of claim 8, wherein the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second device and the third device.

10. The second device according to claim 8, wherein the set of conditions comprises at least one of the following: a first condition associated with suspending data transmission to the third device via the first device, a second condition, the second condition being associated with recovery using one of the at least one candidate cell configurations, A third condition is associated with recovery using the source cell configuration, A fourth condition is associated with discarding the at least one candidate cell configuration and initiating a reestablishment process.

11. The second device of claim 10, wherein the second device is further caused to execute: In response to receiving the second message, determining that the first condition is satisfied; and Based on a determination that the first condition is satisfied, uplink transmission to the third device via the first device is suspended.

12. The second device of claim 10, wherein receiving the at least one indication include: An indication is received from the first device that a handover process is initiated at the first device, the indication corresponding to the first condition.

13. The second device of claim 12, wherein the second device is further caused to execute: In response to receiving the indication corresponding to the first condition, determining that the first condition is satisfied; and Based on a determination that the first condition is satisfied, the uplink transmission to the third device via the first device is suspended.

14. The second device according to claim 8 or claim 13, wherein the second device is further caused to perform: At least one downlink data transmission sent by the third device is received from the first device.

15. The second device according to any one of claims 8 to 13, wherein receiving the at least one indication include: An indication to recover using a target cell configuration is received from the first device, the at least one candidate cell includes the target cell, and the indication corresponds to the second condition.

16. The second device of claim 15, wherein the second device is further caused to execute: In response to receiving the indication, determining that the second condition is satisfied; determining the target cell configuration from the at least one candidate cell configuration based on a determination that the second condition is satisfied; and The target cell configuration is applied and data and / or signaling transmission and reception is resumed.

17. The second device according to any one of claims 8 to 13, wherein receiving the at least one indication include: An indication is received from the first device to recover using the source cell configuration, the indication corresponding to the third condition.

18. The second device of claim 17, wherein the second device is further caused to execute: In response to receiving the indication, determining that the third condition is satisfied; Based on a determination that the third condition is satisfied, discarding the at least one candidate cell configuration; and The source cell configuration is applied and data and / or signaling transmission and reception is resumed.

19. The second device according to any one of claims 8 to 13, wherein receiving the at least one indication include: A reestablishment indication corresponding to the fourth condition is received from the first device.

20. The second device of claim 19, wherein the second device is further caused to perform: Based on a determination that the fourth condition is satisfied, discarding the at least one candidate cell configuration; and Initiate the rebuilding process.

21. The second device according to claim 8, wherein the first device comprises a relay terminal device, the second device comprises a remote terminal device, and the third device comprises a network device.

22. A third device, include: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the third device to at least perform: generating, based on a determination that a handover is to be performed in relation to the first device and the second device, a second message comprising at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device, and each condition in the set of conditions corresponding to at least one indication to be sent from the first device to the second device; sending the second message to the second device via the first device; as well as A first message for initiating the switching is sent to the first device.

23. The third device of claim 22, wherein the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second device and the third device.

24. The third device according to claim 22, wherein the set of conditions includes at least one of the following: a first condition associated with suspending data transmission to the third device via the second device, a second condition, the second condition being associated with recovery using one of the at least one candidate cell configurations, A third condition is associated with recovery using the source cell configuration, A fourth condition is associated with discarding the at least one candidate cell configuration and initiating a reestablishment process.

25. The third device according to claim 22, wherein the first device comprises a relay terminal device, the second device comprises a remote terminal device, and the third device comprises a network device.

26. A method, include: In response to receiving a first message for initiating a handover associated with a first device and a second device from a third device, performing a handover procedure at the first device to a target cell indicated in the first message, the first device acting as a UE-to-network relay for communication between the second device and the third device; as well as Based on the switching process, at least one indication is sent to the second device.

27. A method, include: receiving, via a first device, a second message from a third device, the second message comprising at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; as well as At least one indication corresponding to at least one condition in the set of conditions is received from the first device.

28. A method, include: generating, based on a determination that a handover associated with the first device and the second device is to be performed, a second message at a third device, the second message comprising at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device, and each condition in the set of conditions corresponding to at least one indication to be sent from the first device to the second device; sending the second message to the second device via the first device; as well as A first message for initiating the switching is sent to the first device.

29. A first device, include: means for, in response to receiving from a third device a first message for initiating a handover associated with the first device and a second device, performing a handover procedure to a target cell indicated in the first message, the first device acting as a UE-to-network relay for the second device to communicate with the third device; as well as Means for sending at least one indication to the second apparatus based on the switching process.

30. A second device, include: means for receiving, via a first device, a second message from a third device, the second message comprising at least one candidate cell configuration and a set of conditions associated with the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; as well as Means for receiving at least one indication corresponding to at least one condition of the set of conditions from the first device.

31. A third device, include: means for generating a second message based on a determination that a handover is to be performed in relation to the first apparatus and the second apparatus, the second message comprising at least one candidate cell configuration and a set of conditions associated with the first apparatus, the first apparatus acting as a UE-to-network relay for the second apparatus to communicate with the third apparatus, and each condition in the set of conditions corresponding to at least one indication to be sent from the first apparatus to the second apparatus; means for sending the second message to the second device via the first device; as well as Means for sending a first message to the first device for initiating the handover.

32. A computer readable medium comprising instructions stored thereon, the instructions for causing an apparatus to perform at least the method of claim 26, the method of claim 27, or the method of claim 28.

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